Pigment dispersion liquid and solvent-based ink composition containing the same

ABSTRACT

A pigment dispersion liquid is a pigment dispersion liquid for a solvent-based ink including a base metal pigment and an organic solvent, in which the base metal pigment is subjected to a surface treatment by a fluorine-based compound, and in which the concentration of a fluorine element is from 8 atm % to 35 atm % when an X-ray photoelectron spectroscopy (XPS) analysis of the surface of the base metal pigment is performed.

BACKGROUND

1. Technical Field

The present invention relates to a pigment dispersion liquid and asolvent-based ink composition containing the same.

2. Related Art

In the related art, as a technique of forming a coating film havingmetallic glossy on a printed matter, a foil stamping printing using aprinting ink which is produced from brass, aluminum fine particles, orthe like and which uses gold powder or silver powder as a pigment or ametal foil, a thermal transfer system using a metal foil, or the likehas been used. However, as to those methods, there was a problem in thatit was hard to form a fine pattern or apply to a curved surface part. Inaddition, in a foil stamping printing, there were problems in whichon-demand properties were low, it was hard to cope with multiproductproduction, and it was difficult to perform metallic tone printinghaving gradation.

On the other hand, since a powder coating material containing a metalpigment is a low pollution type coating material in which an organicsolvent is not used, the demand is increasing in various industries.However, in a case of the powder coating material containing the metalpigment, if it is difficult to array the metal pigment in parallel withrespect to a substrate of the coating film, the color tone of thecoating film becomes dark, and thus there was a disadvantage in which itwas difficult to obtain a sufficient metallic feeling. In order toovercome such a disadvantage, for example, in JP-A-2003-213157 andJP-A-2006-169393, a powder for coating material formed by coating thesurface of aluminum particles with a fluorine-based (co)polymer in whicha fluorine (meth)acrylic acid ester is set to an essential monomer isdisclosed. In addition, in JP-A-2009-215411, a powder for coatingmaterial formed by coating the surface of aluminum particles with afluorine-based copolymer in which a fluorine-based polymerizable monomerand a polymerizable monomer having a phosphate group are set to anessential monomer is disclosed.

In recent years, many application examples of an ink jet method in theprinting have been seen, and as an application example among those,there is a metallic printing, and a development for an ink havingmetallic glossy has been proceeded. In the ink jet method, the metallicprinting is excellent in that the metallic printing can suitably beapplied for forming a fine pattern or recording to a curved surfacepart. For example, in JP-A-2012-251070 and JP-A-2013-122008, acomposition for an ultraviolet ray curable type ink jet method includingmetal particles and a polymerizable compound is disclosed.

However, for example, as to aluminum particles formed by coating with afluorine-based (co)polymer as disclosed in JP-A-2003-213157,JP-A-2006-169393, and JP-A-2009-215411, there was a problem in that theglossiness was reduced due to the process of oxidation of aluminumduring a coating treatment. In addition, in a case where such aluminumpigments in which the oxidation is proceeded are dispersed in an organicsolvent, there was a problem in that the aluminum pigments were easilyflocculated with each other, depending on the external environment.Furthermore, once the aluminum pigments are flocculated with each other,there was a problem in that it was not easy to redisperse the aluminumpigments.

In addition, aluminum pigments and metal particles as disclosed inJP-A-2003-213157, JP-A-2006-169393, JP-A-2009-215411, JP-A-2012-251070,and JP-A-2013-122008 are not ones for the purpose of enhancement inwater resistance, however, in a case where these are compounded in asolvent-based ink to record an image, there was a problem in that theweather resistance was not excellent such that an image was whitened byaluminum pigments and metal particles being reacted with moisture in theenvironment.

SUMMARY

An advantage of some aspects of the invention is to provide a pigmentdispersion liquid in which an image excellent in glossiness anddispersibility and excellent in weather resistance in a case of beingcompounded in a solvent-based ink can be recorded and a solvent-basedink composition containing the same.

The invention can be realized in the following forms or applicationexamples.

APPLICATION EXAMPLE 1

According to Application Example 1, there is provided a pigmentdispersion liquid for a solvent-based ink including a base metal pigmentand an organic solvent, in which the base metal pigment is subjected toa surface treatment by a fluorine-based compound, and in which theconcentration of a fluorine element is from 8 atm % to 35 atm % when anX-ray photoelectron spectroscopy (XPS) analysis of the surface of thebase metal pigment is performed.

According to the pigment dispersion liquid of Application Example 1,since a film having a high concentration of a fluorine element is formedon the surface of the base metal pigment, it is possible to effectivelysuppress a decrease in glossiness and the occurrence of flocculationbetween the base metal pigments, caused by the oxidation of the basemetal pigment in the organic solvent.

APPLICATION EXAMPLE 2

In the pigment dispersion liquid of Application Example 1, when an XPSanalysis of the surface of the base metal pigment is performed, theconcentration of phosphorus, sulfur, or nitrogen or the total sum ofthese elements may be 1 atm % or more.

APPLICATION EXAMPLE 3

In the pigment dispersion liquid of Application Example 1 or ApplicationExample 2, the fluorine-based compound may include fluorine and one ormore kinds selected from phosphorus, sulfur, and nitrogen as aconstitutional element.

APPLICATION EXAMPLE 4

In the pigment dispersion liquid of any one of Application Example 1 toApplication Example 3, the fluorine-based compound may have aperfluoroalkyl group.

APPLICATION EXAMPLE 5

In the pigment dispersion liquid of Application Example 4, the number ofcarbon atoms of the perfluoroalkyl group may be from 1 to 6.

APPLICATION EXAMPLE 6

In the pigment dispersion liquid of any one of Application Example 1 toApplication Example 5, when an XPS analysis of the surface of the basemetal pigment is performed, the ratio ([F]/[O]) of the concentration ofa fluorine element ([F]; atm %) to the concentration of an oxygenelement ([O]; atm %) may be from 0.2 to 1.2.

APPLICATION EXAMPLE 7

In the pigment dispersion liquid of any one of Application Example 1 toApplication Example 6, the base metal pigment may include at least onekind selected from aluminum, iron, copper, nickel, and chromium or analloy with other metals.

APPLICATION EXAMPLE 8

In the pigment dispersion liquid of Application Example 7, in a casewhere a base metal included in the base metal pigment is aluminum or analuminum alloy, when an XPS analysis of the surface of the base metalpigment is performed, the ratio ([F]/[Al]) of the concentration of afluorine element ([F]; atm %) to the concentration of an aluminumelement ([Al]; atm %) may be from 0.2 to 1.1.

APPLICATION EXAMPLE 9

In the pigment dispersion liquid of any one of Application Example 1 toApplication Example 8, the shape of the base metal pigment may beplate-shaped.

APPLICATION EXAMPLE 10

In the pigment dispersion liquid of any one of Application Example 1 toApplication Example 9, the molecular weight of the fluorine-basedcompound may be 1,000 or less.

APPLICATION EXAMPLE 11

According to Application Example 11, there is provided a solvent-basedink composition containing the pigment dispersion liquid of any ofApplication Example 1 to Application Example 10, an organic solvent, anda resin.

According to the solvent-based ink composition of Application Example11, since the base metal pigment having a high concentration of afluorine element on the surface is compounded, the glossiness and theweather resistance of the recorded image are remarkably enhanced. Inaddition, since the dispersibility of the base metal pigment in thesolvent-based ink composition becomes good, the discharge stability froma liquid discharging head of a liquid droplet discharging apparatusbecomes good.

APPLICATION EXAMPLE 12

In the solvent-based ink composition of Application Example 11, thefluorine-based compound which is adsorbed or bonded to the base metalpigment included in the pigment dispersion liquid and the fluorine-basedcompound isolated in an ink composition are included and the content ofthe fluorine-based compound isolated in an ink composition may be from0.01% by mass to 3% by mass.

According to the solvent-based ink composition of Application Example12, the base metal pigment to which the fluorine-based compound isadsorbed or bonded becomes difficult to precipitate, in addition, evenif the base metal pigment is precipitated, it is possible to easilyredisperse the base metal pigment, owing to an action of thefluorine-based compound isolated in the ink composition. As this reason,it is considered that as to the fluorine-based compound isolated in theink composition, a molecular assembly such as a micelle or a vesicle inthe ink composition is formed. Since the base metal pigment (to whichthe fluorine-based compound is adsorbed or bonded) is involved in themolecular assembly, it is presumed that the dispersibility is enhanced.

APPLICATION EXAMPLE 13

In the solvent-based ink composition of Application Example 11 orApplication Example 12, a first organic solvent in which the SP valuebased on the Hansen method is from 7 cal/cm³ to 9 cal/cm³ may beincluded as the organic solvent.

APPLICATION EXAMPLE 14

In the solvent-based ink composition of Application Example 13, thecontent of the first organic solvent in an ink composition may be from20% by mass to 95% by mass.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, description will be given of a suitable embodiment of theinvention. The embodiment described below is intended to describe anexample of the invention. In addition, the invention is not limited tothe following embodiment and also includes various Modification Exampleswhich are performed in a range without changing the gist of theinvention.

Hereinafter, description will be given of a pigment dispersion liquidand a solvent-based ink composition in this order.

1. Pigment Dispersion Liquid

A pigment dispersion liquid according to the embodiment is a pigmentdispersion liquid for a solvent-based ink including a base metal pigmentand an organic solvent, in which the base metal pigment is subjected toa surface treatment by a fluorine-based compound, and in which theconcentration of a fluorine element is from 8 atm % to 35 atm % when anX-ray photoelectron spectroscopy (XPS) analysis of the surface of thebase metal pigment is performed.

“A solvent-based ink” in the invention means an ink in which a maincomponent of a liquid medium configuring an ink is an organic solvent.“A main component is an organic solvent” means that the proportion ofthe content of an organic solvent in a liquid medium configuring an inkis 80% by mass or more, preferably 90% by mass or more, more preferably95% by mass or more, and particularly preferably 100% by mass.

“A base metal” in the invention may be a metal having a greaterionization tendency than that of hydrogen and, for example, is a conceptin which a metal single body such as an alkali metal, an alkaline earthmetal, aluminum, iron, zinc, lead, copper, nickel, cobalt, or chromiumas well as an alloy thereof are included.

The base metal pigment included in the pigment dispersion liquidaccording to the embodiment is one in which pigment particles configuredof a material including the base metal (hereinafter, pigment particles,configured of a material including the base metal before being subjectedto the surface treatment, are also referred to as “base particles”) aresubjected to the surface treatment by the fluorine-based compound. Thatis, the base metal pigment included in the pigment dispersion liquidaccording to the embodiment has a structure in which the surface of thepigment particles (the base particles) configured of a materialincluding the base metal is coated with a single layer or a plurality oflayers containing the fluorine-based compound.

1.1. Base Particles

Firstly, description will be given of pigment particles (base particles)configured of a material including a base metal. The base particles maybe one in which a region including at least the vicinity of the surfaceis configured of the base metal and may also be one in which the entireregion is configured of the base metal. In addition, the base particlesmay be one having a base part configured of a nonmetal material and acoating film configured of the base metal which coats the base part.

The base metal which configures the base particles is not particularlylimited as long as the base metal meets the definition of the base metaldescribed above, however, the base metal is preferably aluminum or analuminum alloy from the viewpoint of ensuring the glossiness and theviewpoint of the cost. There was a problem in that the glossiness wasreduced and aluminum became more easily flocculated with each other dueto the process of oxidation of aluminum when aluminum or an aluminumalloy was dispersed in the organic solvent. In contrast, in theinvention, since it is possible to effectively suppress the oxidation ofaluminum by using aluminum or an aluminum alloy coated with a singlelayer or a plurality of layers containing the fluorine-based compound,it is possible to suppress a reduction in glossiness in the organicsolvent and the dispersibility is remarkably enhanced.

In addition, the base particles may be one which is manufactured by anymethod, however, for example, it is preferable to be one obtained byforming a film formed by the base metal on one surface of a sheet-likebase material using an evaporation method, afterward, peeling the filmformed by the base metal from the sheet-like base material and thenpulverizing. An ion plating or spattering method may be used instead ofthe evaporation method. According this method, since plate-shaped baseparticles are obtained, it is possible to effectively exhibit theglossiness or the like in which the base particles originally have.

As a sheet-like base material, for example, a plastic film such aspolyethylene terephthalate can be used. In addition, a mold releaseagent such as silicone oil may be applied onto or a resin layer forpeeling may be formed on the film forming surface of the sheet-like basematerial in advance in order to improve the peelability. As a resin usedfor the resin layer for peeling, for example, polyvinyl alcohol,polyvinyl butyral, polyethylene glycol, polyacrylic acid,polyacrylamide, a cellulose derivative such as cellulose acetatebutyrate, a modified nylon resin, and the like are included. The peelingand pulverizing described above are performed by adding an externalforce, for example, with irradiating the film with ultrasonic waves orstirring by a homogenizer or the like in a nonaqueous-based medium.

As a nonaqueous-based medium in a case of performing the peeling andpulverizing by the method as described above, alcohols such as methanol,ethanol, propanol, or butanol; a hydrocarbon-based compound such asn-heptane, n-octane, decane, dodecane, tetradecane, toluene, xylene,cymene, durene, indene, dipentene, tetrahydronaphthalene,decahydronaphthalene, or cyclohexylbenzene; an ether-based compound suchas ethylene glycol dimethyl ether, ethylene glycol diethyl ether,ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether,diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether,diethylene glycol monobutyl ether acetate, diethylene glycol n-butylether, tripropylene glycol dimethyl ether, triethylene glycol diethylether, propylene glycol monomethyl ether acetate, 1,2-dimethoxyethane,bis(2-methoxyethyl)ether, or p-dioxane; a polar organic solvent such aspropylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone,N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide,cyclohexanone, or acetonitrile can be suitably used. By using such anonaqueous-based medium, it is possible to prevent the involuntaryoxidation of the base particles or the like and reduce variations insize, shape, and characteristics between each particle.

Moreover, since the preferable average particle diameter and averagethickness of the base particles are almost the same as the averageparticle diameter and the average thickness of the base metal pigmentdescribed below, description will be omitted here.

1.2. Fluorine-based Compound

Next, description will be given of a fluorine-based compound used forthe surface treatment of the base particles. As described above, thebase metal pigment included in the pigment dispersion liquid accordingto the embodiment is one in which the base particles are subjected tothe surface treatment by the fluorine-based compound. As such afluorine-based compound, a compound including fluorine and one or morekinds selected from phosphorus, sulfur, and nitrogen as a constitutionalelement can be preferably used, and specifically, fluorine-basedphosphonic acid, fluorine-based carboxylic acid, fluorine-based sulfonicacid, a salt thereof, and the like are included. If these fluorine-basedcompounds are used, it is possible to form a coating film by bonding aphosphoric acid group, a carboxyl group, a sulfonic acid group, or thelike to the surface of the base particles. In the invention, since it ispossible to effectively suppress the oxidation of the base metal pigmentby using the base metal pigment coated with a single layer or aplurality of layers containing the fluorine-based compound, it ispossible to ensure the glossiness in the organic solvent and remarkablyenhance the dispersibility. Among those, since a phosphoric acid groupis particularly excellent in bonding capability to the surface of thebase particles, fluorine-based phosphonic acid and a salt thereof aremore preferable.

As fluorine-based phosphonic acid and a salt thereof, one having astructure represented by the following general formula (1) ispreferable.

In the formula (1), R¹ is each independently one kind of a groupselected from among the following structural formulae and M is eachindependently a hydrogen atom, a hydrocarbon group, a monovalent metalion, an ammonium ion, or —NR²R³R⁴. R², R³, and R⁴ are respectively ahydrogen atom or a C₂H₄OH group, however, a case where all of R², R³,and R⁴ are hydrogen atoms is excluded. n is an integer from 1 to 3, m isan integer from 1 to 12, and 1 is an integer from 1 to 12.

In the formula (1), m is an integer from 1 to 12, however, is preferablyan integer from 1 to 8 and is more preferably an integer from 1 to 5. Inaddition, 1 is an integer from 1 to 12, however, is preferably aninteger from 1 to 10 and is more preferably an integer from 1 to 6. Whenm and 1 are in the preferable range described above, the effect asdescribed above is more prominently exhibited.

As fluorine-based phosphonic acid, a compound represented by thefollowing general formula (2) is particularly preferable from theviewpoint of being excellent in balance between the adsorption abilityto the surface of the base particles and the enhancement of the weatherresistance.

In the formula (2), m is an integer from 1 to 12, however, is preferablyan integer from 1 to 8 and is more preferably an integer from 1 to 5. Inaddition, 1 is an integer from 1 to 12, however, is preferably aninteger from 1 to 10 and is more preferably an integer from 1 to 6. Whenm and l are in the preferable range described above, the effect asdescribed above is more prominently exhibited.

As fluorine-based carboxylic acid and a salt thereof, one having astructure represented by the following general formula (3) ispreferable.

In the formula (3), R⁵ is one kind of a group selected from among thefollowing structural formulae and M is a hydrogen atom, a monovalentmetal ion, or an ammonium ion. m is an integer from 1 to 12, however, ispreferably an integer from 1 to 8 and is more preferably an integer from1 to 5. In addition, l is an integer from 1 to 12, however, ispreferably an integer from 1 to 10 and is more preferably an integerfrom 1 to 6.

As fluorine-based sulfonic acid and a salt thereof, one having astructure represented by the following general formula (4) ispreferable.

In the formula (4), R⁶ is one kind of a group selected from among thefollowing structural formulae and M is a hydrogen atom, a monovalentmetal ion, or an ammonium ion. m is an integer from 5 to 17 and l is aninteger from 1 to 12.

In addition, the fluorine-based compound preferably has a perfluoroalkylgroup (C_(n)F_(2n+1)) in at least a part of a structure thereof and thenumber of carbon atoms of the perfluoroalkyl group is more preferablyfrom 1 to 6. The base metal pigment excellent in glossiness anddispersibility is easily obtained and there is a tendency in that theweather resistance becomes better when an image is recorded, owing tothe fluorine-based compound having such a structure.

Moreover, the molecular weight of the fluorine-based compound ispreferably 1,000 or less. In a case where the fluorine-based compoundwhich is adsorbed to the surface of the base particles is afluorine-based polymer described in, for example, JP-A-2003-213157,JP-A-2006-169393, JP-A-2009-215411, or the like, there are some caseswhere not only the glossiness is damaged since the coating film becomestoo thick but the dispersibility is significantly reduced since theinteraction between the base metal pigments on which the coating film isformed becomes stronger. Therefore, the film formed on the surface ofthe base particles is preferably set to a monomolecular film formed bythe fluorine-based compound having a molecular weight of 1,000 or less.

1.3. Method of Manufacturing Pigment Dispersion Liquid

The pigment dispersion liquid according to the embodiment can bemanufactured, for example, as follows.

Firstly, a dispersion liquid in which the base particles described aboveare dispersed in the nonaqueous-based medium is prepared. After thedispersion liquid is diluted with the same kind or a different kind ofnonaqueous-based medium as necessary, the base particles are subjectedto a pulverization treatment by irradiating with ultrasonic waves untilthe average particle diameter of the base particles becomes 1 μm orless. The time for the pulverization treatment is not particularlylimited, however, is normally from 3 hours to 24 hours. In addition, asa specific example of the nonaqueous-based medium used for dilution, thesame nonaqueous-based medium as the nonaqueous-based medium in a case ofperforming the peeling and pulverizing exemplified above is included.

Next, the coating film of the fluorine-based compound is formed on thesurface of the base particles by adding the fluorine-based compound tothe dispersion liquid in which the base particles in which thepulverization treatment has been completed are dispersed in thenonaqueous-based medium and irradiating the dispersion liquid withultrasonic waves. In doing so, the base metal pigment in which thesurface of the base particles is treated by the fluorine-based compoundis obtained. The additive amount of the fluorine-based compound is from1 part by mass to 50 parts by mass, preferably from 2 parts by mass to40 parts by mass, and more preferably from 4.5 parts by mass to 30 partsby mass, with respect to 100 parts by mass of the base particles. Inaddition, when the surface treatment is performed by irradiating withultrasonic waves, the heating may be performed. As a heatingtemperature, it is preferable to be 40° C. or higher. It is consideredthat a covalent bond is formed between the surface of the base particlesand the fluorine-based compound by performing a heating treatment, andthus a bonding force is strengthened.

The surface treatment of the base particles by the fluorine-basedcompound may be a treatment in which the surface of the base particlesis directly treated, however, the treatment by the fluorine-basedcompound may be performed with respect to the base particles which aretreated with an acid or a base in advance. Thereby, it is possible tomore certainly perform the chemical modification on the surface of thebase particles by the fluorine-based compound, and thus it is possibleto more effectively exhibit the effect according to the invention asdescribed above. In addition, even in a case where an oxide coating filmis formed on the surface of particle to be the base particles before thesurface treatment by the fluorine-based compound is performed, since theoxide coating film can be removed and the surface treatment byfluorine-based compound can be performed in a state in which the oxidecoating film is removed, it is possible to make the glossiness of thebase metal pigment which is manufactured excellent. As such an acid, forexample, a proton acid such as hydrochloric acid, sulfuric acid,phosphoric acid, nitric acid, boric acid, acetic acid, carbonic acid,formic acid, benzoic acid, chlorous acid, hypochlorous acid, sulfurousacid, hyposulphurous acid, nitrous acid, hyponitrous acid, phosphorousacid, or hypophosphorous acid can be used. On the other hand, as a base,for example, sodium hydroxide, potassium hydroxide, calcium hydroxide,or the like can be used.

One obtained in the processes so far may be used as a pigment dispersionliquid without any change, however, after this, it is preferable tofurther perform a solvent substitution. It is possible to remove excessfluorine-based compounds included in the pigment dispersion liquid byperforming the solvent substitution. As a specific method of the solventsubstitution, the dispersion liquid containing the base metal pigmentwhich is subjected to a fluorine treatment obtained as described aboveis centrifuged to remove a supernatant liquid, an appropriate amount ofnonaqueous-based medium which is substituted is added thereto, and thebase metal pigment is dispersed in the nonaqueous-based mediumsubstituted by irradiating with ultrasonic waves. In doing so, thepigment dispersion liquid in which the base metal pigment is dispersedis obtained. In addition, it is also preferable that the pigmentdispersion liquid thus obtained be further subjected to the heatingtreatment. It is presumed that the fluorine-based compound which ision-bonded to the surface of the base particles is dehydrated to form acovalent bond by heating and the base particles can be more firmlybonded to the fluorine-based compound, and thus the effect according tothe invention as described above can be more effectively exhibited. Theheating temperature is preferably 50° C. or higher and more preferably60° C. or higher. The heating treatment time is preferably from 1 day to10 days.

In addition, as a nonaqueous-based medium used for substituting, a polarorganic solvent is preferable and as a specific example thereof, thesame nonaqueous-based medium as the nonaqueous-based medium in a case ofperforming the peeling and pulverizing exemplified above is included.

In addition, a surfactant may be further added to the nonaqueous-basedmedium used for substituting. As a surfactant which can be added to thenonaqueous-based medium, a fluorine-based surfactant and/or asilicone-based surfactant are preferable. The proportion of the contentof the surfactant in the nonaqueous-based medium is preferably 3% bymass or less, more preferably from 0.01% by mass to 2% by mass, andparticularly preferably from 0.1% by mass to 1% by mass. When theproportion of the content of the surfactant is in the range describedabove, there is a tendency in that the dispersibility of the base metalpigment is more enhanced. In addition, when the image is recorded, afunction as a slipping agent is exhibited and there are some cases wherean effect for enhancing the abrasion resistance of the image isobtained.

As a fluorine-based surfactant, for example, MEGAFACE F-430, MEGAFACEF-444, MEGAFACE F-472SF, MEGAFACE F-475, MEGAFACE F-477, MEGAFACE F-552,MEGAFACE F-553, MEGAFACE F-554, MEGAFACE F-555, MEGAFACE F-556, MEGAFACEF-558, MEGAFACE R-94, MEGAFACE RS-75, and MEGAFACE RS-72-K(hereinbefore, all trade names, manufactured by DIC Corporation); EFTOPEF-351, EFTOP EF-352, EFTOP EF-601, EFTOP EF-801, and EFTOP EF-802(hereinbefore, all trade names, manufactured by Mitsubishi MaterialsCorporation); Ftergent 222F, Ftergent 251, and FTX-218 (hereinbefore,all trade names, manufactured by NEOS COMPANY LIMITED); SURFLON SC-101and SURFLON KH-40 (hereinbefore, all trade names, manufactured by AGCSEIMI CHEMICAL CO., LTD.), and the like are included.

As a silicone-based surfactant, for example, BYK-300, BYK-306, BYK-310,BYK-320, BYK-330, BYK-344, BYK-346, BYK-UV3500, and BYK-UV3570(hereinbefore, all trade names, manufactured by BYK Japan KK); KP-341,KP-358, KP-368, KF-96-50CS, and KF-50-100CS (hereinbefore, all tradenames, manufactured by Shin-Etsu Chemical Co., Ltd.), and the like areincluded.

The proportion of the content of the base metal pigment in the pigmentdispersion liquid according to the embodiment is not particularlylimited, however, is preferably from 1% by mass to 10% by mass. When theproportion of the content of the base metal pigment in the pigmentdispersion liquid is in the range described above, the dispersibility ofthe base metal pigment in the pigment dispersion liquid easily becomesgood and it becomes possible to store the base metal pigment for a longperiod.

1.4. Physical Property of Base Metal Pigment 1.4.1. XPS Analysis

According to an X-ray photoelectron spectroscopy (XPS) analysis, it ispossible to obtain information of the top surface (approximately severalnm) of the base metal pigment. The XPS analysis is an analysis method ofdetecting a photoelectron emitted by irradiating a sample with an X-rayin ultrahigh vacuum. Since the photoelectron which is emitted is causedby a core electron of a target atom and the energy thereof is determinedfor each element, it is possible to perform the qualitative analysis byknowing an energy value.

When the XPS analysis (radiation source: Al—Kα ray, irradiation angle:45°, detection angle: 90°) is performed, the base metal pigment includedin the pigment dispersion liquid according to the embodiment ischaracterized in that the concentration of a fluorine element is from 8atm % to 35 atm %. This indicates that the fluorine-based compounddensely exists on the top surface (approximately several nm) of the basemetal pigment. When the concentration of a fluorine element in the basemetal pigment is in the range described above, since it is possible toeffectively suppress the oxidation of the base metal pigment, areduction in glossiness in the organic solvent is suppressed and thedispersibility is remarkably enhanced. In a case where the concentrationof a fluorine element in the base metal pigment is less than the rangedescribed above, the effect for suppressing the oxidation of the basemetal pigment easily becomes insufficient, the glossiness is easily lostin the organic solvent, and the dispersibility easily deteriorates inthe organic solvent. On the other hand, the base metal pigment in whichthe concentration of a fluorine element in the base metal pigmentexceeds the range described above has not been obtained even by thestudy of the inventors and technical difficulties are accompanied.

As to the base metal pigment included in the pigment dispersion liquidaccording to the embodiment, when the XPS analysis (radiation source:Al—Kα ray, irradiation angle: 45°, detection angle: 90°) is performed,it is preferable that the concentration of phosphorus, sulfur, ornitrogen or the total sum of these elements be 1 atm % or more. Thisindicates that the fluorine-based compound such as fluorine-basedphosphonic acid, fluorine-based sulfonic acid, and a salt thereof isadsorbed to the top surface (approximately several nm) of the base metalpigment and densely exists. In a case where the concentration ofphosphorus, sulfur, or nitrogen or the total sum of these elements is 1atm % or more, this indicates that the film of the fluorine-basedcompound is formed with a good film thickness on the surface of the basemetal pigment. Thereby, since it is possible to effectively suppress theoxidation of the base metal pigment, a reduction in glossiness in theorganic solvent is suppressed and the dispersibility in the organicsolvent is remarkably enhanced.

As to the base metal pigment included in the pigment dispersion liquidaccording to the embodiment, when the XPS analysis (radiation source:Al—Kα ray, irradiation angle: 45°, detection angle: 90°) is performed,the ratio ([F]/[O]) of the concentration of a fluorine element ([F]; atm%) to the concentration of an oxygen element ([O]; atm %) is preferablyfrom 0.2 to 1.2. Since there is a tendency in that the concentration ofan oxygen element depends on oxygen derived from a hydroxide of the basemetal included in the base metal pigment, this also indicates that thefluorine-based compound densely exists on the top surface (approximatelyseveral nm) of the base metal pigment. When the ratio ([F]/[O]) of thebase metal pigment is in the range described above, since the balancebetween the concentration of a fluorine element and the concentration ofan oxygen element on the surface of the base metal pigment becomes goodand it is possible to effectively suppress the oxidation of the basemetal pigment, a reduction in glossiness in the organic solvent issuppressed and the dispersibility in the organic solvent is remarkablyenhanced.

As to the base metal pigment included in the pigment dispersion liquidaccording to the embodiment, in a case of using aluminum or an aluminumalloy as base particles, when the XPS analysis (radiation source: Al—Kαray, irradiation angle: 45°, detection angle: 90°) is performed, theratio ([F]/[Al]) of the concentration of a fluorine element ([F]; atm %)to the concentration of an aluminum element ([Al]; atm %) is preferablyfrom 0.2 to 1.1. This also indicates that the fluorine-based compounddensely exists on the top surface (approximately several nm) of the basemetal pigment. When the ratio ([F]/[Al]) is in the range describedabove, since the balance between the concentration of an aluminumelement and the concentration of a fluorine element on the surface ofthe base metal pigment becomes good and it is possible to effectivelysuppress the oxidation of the base metal pigment, a reduction inglossiness in the organic solvent is suppressed and the dispersibilityin the organic solvent is remarkably enhanced.

Furthermore, since an electronic state is changed depending on anenvironment (a chemical state) in which atoms are placed, it is possibleto perform a chemical structural analysis by using the fact that a peakposition is slightly shifted. Specifically, it is possible to calculatethe proportion of each component by approximating a componentcorresponding to each chemical state using the Voigt function (thefollowing separation expression) to divide the peak.

$y = {y_{0} + {{A \cdot \frac{2\; \ln \; 2}{\pi^{3/2}}}{\frac{w_{L}}{w_{G}^{2}} \cdot {\int_{- \infty}^{\infty}{\frac{e^{- t^{2}}}{\left( {\sqrt{\ln \; 2}\frac{w_{L}}{w_{G}}} \right)^{2} + \left( {{\sqrt{4\; \ln \; 2}\frac{x - x_{c}}{w_{G}}} - t} \right)^{2}}{t}}}}}}$

(y_(O)=offset, x_(C)=center, A=Amplitude, w_(G)=Gaussian width,w_(L)=Lorentzian width)

In a case of the base metal pigment which is subjected to the surfacetreatment by fluorine-based phosphonic acid (salt), the base metalpigment has the peak from 190 eV to 192 eV when approximating acomponent using the Voigt function to divide the peak in an X-rayphotoelectron spectroscopy spectrum. By bonding fluorine-basedphosphonic acid (salt) to the surface of the base particles, thechemical shift of the peak of P (phosphorus) occurs between 190 eV and192 eV. By existing the peak from 190 eV to 192 eV, fluorine-basedphosphonic acid (salt) is certainly bonded to the surface of the baseparticles. Thereby, since it is possible to effectively suppress theoxidation of the base metal pigment, a decrease in glossiness in theorganic solvent is suppressed and the dispersibility in the organicsolvent is remarkably enhanced.

In addition, In a case of the base metal pigment which is subjected tothe surface treatment by the fluorine-based compound, the base metalpigment has the peaks at 291 eV and 293 eV in an X-ray photoelectronspectroscopy spectrum. Since the peak at 291 eV is a peak derived from—CF₂— and the peak at 293 eV is a peak derived from —CF₃, in a casewhere the peaks are recognized at 291 eV and 293 eV, it is understoodthat the fluorine-based compound is bonded to the surface of the baseparticles.

1.4.2. Shape

The shape of the base metal pigment included in the pigment dispersionliquid according to the embodiment may be any shape such as a sphericalshape, a spindle shape, or a needle shape, however, a plate shape ispreferable. In a case where the shape of base metal pigment isplate-shaped, since the light reflectivity becomes good, it is possibleto record the image excellent in glossiness.

In the invention, “plate-shaped” means a shape in which an area whenobserving from a predetermined angle (when viewing in planar view) isbigger than an area when observing from an angle orthogonal to theobservation direction and, in particular, the ratio (S₁/S₀) of an areaS₁ [μm²] when observing from a direction in which the projected areabecomes maximum (when viewing in planar view) to an area S₀ [μm²] whenobserving from a direction in which an area when observing becomesmaximum among directions orthogonal to the observation direction ispreferably 2 or more, more preferably 5 or more, and particularlypreferably 8 or more. As this value, for example, the observation of thearbitrary 10 particles is performed and an average value of valuescalculated as to these particles can be employed.

1.4.3. Average Particle Diameter and Average Thickness

As to the base metal pigment included in the pigment dispersion liquidaccording to the embodiment, the average particle diameter is preferablyfrom 0.25 μm to 3 μm and more preferably from 0.5 μm to 1.5 μm. Inaddition, as to the base metal pigment included in the pigmentdispersion liquid according to the embodiment, the average thickness ispreferably from 1 nm to 100 nm and more preferably from 5 nm to 50 nm.When the average particle diameter and the average thickness of the basemetal pigment are in the ranges described above, in a case where thebase metal pigment is applied to the solvent-based ink composition, itis possible to record the image excellent in smoothness of the coatingfilm and excellent in glossiness. In addition, it is possible tomanufacture the pigment dispersion liquid with high productivity and itis also possible to prevent the involuntary modification of the basemetal pigment during manufacturing the solvent-based ink composition.

This average particle diameter is represented by the 50% averageparticle diameter (R50) of an equivalent circle diameter determined froman area of a projected image of the base metal pigment obtained by aparticle image analyzer. “An equivalent circle diameter” means adiameter of a circle when assuming the circle having the same area as anarea of a projected image of the base metal pigment obtained by using aparticle image analyzer. For example, in a case where a projected imageof the base metal pigment is a polygon, a diameter of a circle obtainedby converting the projected image into the circle is referred to as anequivalent circle diameter of the base metal pigment.

It is possible to measure the area of the projected image and theequivalent circle diameter of the base metal pigment using a particleimage analyzer. As such a particle image analyzer, for example, a flowtype particle image analyzer FPIA-2100, FPIA-3000, and FPIA-3000S(hereinbefore, manufactured by Sysmex Corporation), and the like areincluded. Moreover, the average particle diameter of the equivalentcircle diameter is a particle diameter based on the number. In addition,as a measurement method in a case of using FPIA-3000 or FPIA-3000S, amethod of measuring in the HPF measurement mode using a highmagnification imaging unit is included as an example.

Moreover, the average thickness means a thickness in which a side faceimage of the base metal pigment is photographed using a transmissionelectron microscope (TEM) or a scanning electron microscope (SEM), thethicknesses of base metal pigments are respectively determined, andthese are averaged. Type “JEM-2000EX” manufactured by JEOL Ltd. and thelike as a transmission electron microscope (TEM) and Type “S-4700”manufactured by Hitachi High-Technologies Corporation and the like as ascanning electron microscope are respectively included.

2. Solvent-Based Ink Composition

The solvent-based ink composition according to the embodiment containsthe pigment dispersion liquid described above, an organic solvent, and aresin. Since the solvent-based ink composition according to theembodiment contains the above-described pigment dispersion liquidexcellent in dispersibility of the base metal pigment, even in a case ofbeing applied to a liquid droplet discharging apparatus, the clogging ofa nozzle due to the base metal pigments being flocculated with eachother is suppressed. Thereby, the discharge stability of ink becomesgood. In addition, since it is possible to reduce the surface freeenergy due to an effect of fluorine in the fluorine-based compound whichis bonded to the surface of the base metal pigment, the leafing of thebase metal pigment easily occurs when the ink is dried, and thus it ispossible to record the image excellent in glossiness. Furthermore, it ispossible to record the image excellent in weather resistance owing tothe water repellent effect of fluorine in the fluorine-based compoundwhich is bonded to the surface of the base metal pigment.

The content of the base metal pigment in the solvent-based inkcomposition according to the embodiment is preferably from 0.1% by massto 5.0% by mass, more preferably from 0.25% by mass to 3.0% by mass, andparticularly preferably from 0.5% by mass to 2.5% by mass, with respectto the total mass of the solvent-based ink composition.

It is preferable that The solvent-based ink composition according to theembodiment include the fluorine-based compound which is adsorbed orbonded to the base metal pigment included in the pigment dispersionliquid and the fluorine-based compound isolated in the ink composition.In addition, the content of the fluorine-based compound isolated in theink composition is preferably from 0.01% by mass to 3% by mass and morepreferably from 0.05% by mass to 1.5% by mass. When the fluorine-basedcompound isolated in the ink composition exists with the contentdescribed above, the base metal pigment to which the fluorine-basedcompound is adsorbed or bonded becomes difficult to precipitate owing toan action of the isolated fluorine-based compound or even if the basemetal pigment is precipitated, it is possible to easily redisperse thebase metal pigment.

This mechanism is presumed as follows. It is considered that as to thefluorine-based compound isolated in the ink composition, a molecularassembly such as a micelle or a vesicle in the ink composition isformed. Since the base metal pigment (to which the fluorine-basedcompound is adsorbed or bonded) is involved in this molecular assembly,it is presumed that the dispersibility is enhanced.

In order to have the fluorine-based compound isolated in the inkcomposition with the predetermined amount, when the pigment dispersionliquid described above is prepared, the fluorine-based compound may beexcessively added or when the ink composition is prepare, thefluorine-based compound may be added afterwards.

The solvent-based ink composition according to the embodiment is onewhich is mainly composed of an organic solvent as a liquid medium asdefined above. Such an organic solvent, for example, alcohols (forexample, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol,isopropyl alcohol, fluoroalcohol, or the like), ketones (for example,acetone, methyl ethyl ketone, cyclohexanone, or the like), esters (forexample, methyl acetate, ethyl acetate, propyl acetate, butyl acetate,methyl propionate, ethyl propionate, γ-butyrolactone, δ-valerolactone,ε-caprolactone, or the like), ethers (for example, diethyl ether,dipropyl ether, tetrahydrofuran, dioxane, glycol ether, or the like), anaromatic hydrocarbon (xylene, ethylbenzene, or the like), an aliphatichydrocarbon (hexane or the like), an alicyclic hydrocarbon (cyclohexaneor the like), or the like can be used. These organic solvents can be useas one kind alone or can be used in combination of two or more kindsthereof.

Among these organic solvents, it is preferable to contain one or morekinds of alkylene glycol ethers which are liquids at normal temperatureunder normal pressure.

As to an alkylene glycol ether, there are an ethylene glycol-based etherand a propylene glycol-based ether in which each group of aliphatic suchas methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, hexyl, and2-ethylhexyl, and allyl and phenyl having a double bond is set to abase, and an alkylene glycol ether is colorless and also has less odor,and is a liquid at normal temperature, provided with characteristics ofboth alcohols and ethers since an alkylene glycol ether has an ethergroup and a hydroxyl group in a molecule. In addition, there are amonoether type in which only one hydroxyl group is substituted and adiether type in which both hydroxyl groups are substituted and these canbe used in combination of a plurality of kinds thereof.

A most preferable aspect of the organic solvent contained in thesolvent-based ink composition according to the embodiment is a mixtureof an alkylene glycol monoether, an alkylene glycol diether, andlactone. By setting a combination of the organic solvents thus, it ispossible to further more enhance an effect of the invention.

As an alkylene glycol monoether, ethylene glycol monomethyl ether,ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether,ethylene glycol monobutyl ether, ethylene glycol monohexyl ether,ethylene glycol monophenyl ether, diethylene glycol monomethyl ether,diethylene glycol monoethyl ether, diethylene glycol monobutyl ether,triethylene glycol monomethyl ether, triethylene glycol monoethyl ether,triethylene glycol monobutyl ether, tetraethylene glycol monomethylether, tetraethylene glycol monoethyl ether, tetraethylene glycolmonobutyl ether, propylene glycol monomethyl ether, propylene glycolmonoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycolmonoethyl ether, and the like are included.

As an alkylene glycol diether, ethylene glycol dimethyl ether, ethyleneglycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycoldimethyl ether, diethylene glycol diethyl ether, diethylene glycoldibutyl ether, diethylene glycol methyl ethyl ether, triethylene glycoldimethyl ether, triethylene glycol diethyl ether, triethylene glycoldibutyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycoldiethyl ether, tetraethylene glycol dibutyl ether, propylene glycoldimethyl ether, propylene glycol diethyl ether, dipropylene glycoldimethyl ether, dipropylene glycol diethyl ether, and the like areincluded.

As lactone, α-ethyl lactone, α-acetolactone, β-propiolactone,γ-butyrolactone, δ-valerolactone, ε-caprolactone, ζ-enantio lactone,η-caprylolactone, γ-valerolactone, γ-heptalactone, γ-nonalactone,β-methyl-δ-valerolactone, 2-butyl-2-ethyl propiolactone, α,α-diethylpropiolactone, and the like are included.

In addition, it is also preferable that a first organic solvent in whichthe SP value based on the Hansen method is from 7 cal/cm³ to 9 cal/cm³be included. When the first organic solvent is included in thesolvent-based ink composition according to the embodiment, it ispossible to dissolve the fluorine-based compound in the ink composition.Thereby, it is possible to set the content of the isolatedfluorine-based compound in the ink composition to a range from 0.01% bymass to 3% by mass by desorbing the fluorine-based compound which existson the surface of the base metal pigment or adding the fluorine-basedcompound into the ink composition afterwards.

As such a first organic solvent, for example, xylene (8.95),ethylbenzene (8.93), butyl acetate (8.70), oleic acid (8.69), dodecylacrylate (8.63), cyclohexane (8.40), diethyl ether (7.82), hexane(7.45), ethyl octanoate (8.3), 3-methoxybutyl acetate (8.71),3,5,5-trimethyl-2-cyclohexen-1-one (8.87), butoxy propanol (8.9),diethylene glycol butyl methyl ether (8.1), diethylene glycolmonoisobutyl ether (8.7), diethylene glycol diethyl ether (8.1),diethylene glycol dibutyl ether (7.7), diethylene glycol ethyl methylether (8.3), diethylene glycol isopropyl methyl ether (7.9), dipropyleneglycol dimethyl ether (7.88), dipropylene glycol n-butyl ether (8.2),triethylene glycol dimethyl ether (8.7), triethylene glycol butyl methylether (8.0), tripropylene glycol dimethyl ether (7.4), tetraethyleneglycol dimethyl ether (8.7), ethylene glycol monomethyl ether acetate(8.96), ethylene glycol monoethyl ether acetate (8.91), ethylene glycolmonobutyl ether acetate (8.85), diethylene glycol monobutyl etheracetate (8.94), dipropylene glycol monomethyl ether acetate (8.6), andthe like are included. Moreover, the numbers in brackets represent theSP values based on the Hansen method.

Moreover, “the SP value” in the specification is referred to as thecompatibility parameter and can also be referred to as the solubilityparameter. The SP value means a value calculated using the Hansenmathematical expression indicated below. The Hansen solubility parameteris one in which the solubility parameter introduced by Hildebrand isdivided into three components of a dispersion term δd, a polarity termδp, and a hydrogen bond term δh to represent in three-dimensional space.In the specification, the SP value is represented by δ [(cal/cm³)^(0.5)]and the value calculated using the following mathematical expression isused.

δ[(cal/cm³)^(0.5)]=(δd ² +δp ² +δh ²)^(0.5)

Moreover, the dispersion term δd, the polarity term δp, and the hydrogenbond term δh were determined by Hansen or the successors of researchthereof many times and, for example, are published in VII-698 to 711 inPolymer Handbook (the fourth edition). In addition, the Hansensolubility parameters on many solvents and resins have been examinedand, for example, these solubility parameters are described inIndustrial Solvents Handbook (written by Wesley L. Archer).

The content of the first organic solvent in the ink compositionaccording to the embodiment is preferably from 20% by mass to 95% bymass and more preferably 30% by mass to 90% by mass.

As a resin used for the solvent-based ink composition according to theembodiment, for example, an acrylic resin, a styrene-acrylic resin, arosin-modified resin, a terpene-based resin, a polyester resin, apolyamide resin, an epoxy resin, a vinyl chloride resin, a vinylchloride-vinyl acetate copolymer, a cellulose-based resin (for example,cellulose acetate butyrate, hydroxypropyl cellulose), polyvinyl butyral,polyacryl polyol, polyvinyl alcohol, polyurethane, and the like areincluded.

In addition, nonaqueous-based emulsion type polymer fine particles(NAD=Non Aqueous Dispersion) can also be used as a resin. This means adispersion liquid in which fine particles of a polyurethane resin, anacrylic resin, an acrylic polyol resin, or the like are stably dispersedin the organic solvent. As a specific product name, SANPRENE IB-501,SANPRENE IB-F370, and the like manufactured by Sanyo ChemicalIndustries, Ltd. are included as a polyurethane resin and N-2043-60MEX,N-2043-AF-1, and the like manufacture by Harima Chemicals, Inc. areincluded as an acrylic polyol resin.

These resins can be used as one kind alone or can be used in combinationof two or more kinds thereof.

The content of the resin (the solid content) in the solvent-based inkcomposition according to the embodiment is preferably from 0.05% by massto 10% by mass, more preferably from 0.1% by mass to 5% by mass, andparticularly preferably from 0.15% by mass to 2% by mass, with respectto the total mass of the solvent-based ink composition. When the contentof the resin is in the range described above, it is possible to furthermore enhance fixing properties to a recording medium of the base metalpigment.

At least one kind of a surfactant selected from a group consisting of afluorine-based surfactant and a silicone-based surfactant may be furtheradded to the solvent-based ink composition according to the embodiment.The content of the surfactant in the solvent-based ink compositionaccording to the embodiment is preferably 3% by mass or less, morepreferably from 0.01% by mass to 2% by mass, and particularly preferablyfrom 0.1% by mass to 1% by mass, with respect to the total mass of thesolvent-based ink composition. When the content of the surfactant is inthe range described above, the wettability to the recording medium ofthe solvent-based ink composition is improved and it is possible tofurther more enhance fixing properties to the recording medium of thebase metal pigment. In addition, a function as a slipping agent isexhibited on the recorded image and an effect for enhancing the abrasionresistance of the image is obtained.

A fluorine-based surfactant and a silicone-based surfactant like the oneexemplified above, which can be added when the pigment dispersion liquidis prepared, can be used. These surfactants can be used as one kindalone or can be used in combination of two or more kinds thereof.

The solvent-based ink composition according to the embodiment can beprepared by a well-known general method. For example, the solvent-basedink composition can be obtained by firstly mixing and dissolving theorganic solvent, the resin, and the additive agent to produce an inksolvent, afterwards, adding the pigment dispersion liquid containing thebase metal pigment described above to the ink solvent, furthermore,mixing and stirring the ink solvent at normal temperature under normalpressure.

As to the solvent-based ink composition according to the embodiment, anapplication thereof is not particularly limited and, for example, thesolvent-based ink composition can be applied to a writing material, astamp, a recorder, a pen plotter, a liquid droplet dischargingapparatus, or the like.

The viscosity at 20° C. of the solvent-based ink composition accordingto the embodiment is preferably from 2 mPa·s to 10 mPa·s and morepreferably from 3 mPa·s to 5 mPa·s. When the viscosity at 20° C. of thesolvent-based ink composition is in the range described above, since thesolvent-based ink composition from a liquid droplet discharging nozzleis discharge with an appropriate amount and the flying curving and thescattering of the solvent-based ink composition can be further reduced,it is possible to suitably use the solvent-based ink composition for aliquid droplet discharging apparatus.

In addition, the surface tension at 20° C. of the solvent-based inkcomposition according to the embodiment is preferably from 20 mN/m to 50mN/m. When the surface tension becomes less than 20 mN/m, thesolvent-based ink composition is wetted and spreads, or oozed on thesurface of the liquid droplet discharging head, and thus ink dropletssometimes become difficult to discharge, and when the surface tensionexceeds 50 mN/m, the solvent-based ink composition is not wetted anddoes not spread on the surface of the recording medium, and thus it issometimes difficult to perform successful printing.

3. Example

Hereinafter, specific description will be given of the invention basedon Examples, however, the invention is not limited to Examples. “Part”and “%” in Example and Comparative Example are on the mass basis unlessotherwise mentioned.

3.1. Manufacturing Pigment Dispersion Liquid for Solvent-Based Ink3.1.1. Example 1

Firstly, a film (the arithmetical mean surface roughness Ra was 0.02 μmor less) which had the smooth surface and was made of polyethyleneterephthalate was prepared.

Next, cellulose acetate butyrate (the butylation ratio from 35% to 39%)was applied onto the entire one surface of this film. Next, a film(hereinafter, also simply referred to as “an aluminum film”) configuredof aluminum was formed on the surface side onto which cellulose acetatebutyrate was applied using an evaporation method.

Next, the film on which the aluminum film was formed was put intodiethylene glycol diethyl ether to be irradiated with ultrasonic waves.Thereby, a dispersion liquid of plate-shaped particles (particles to bethe base particles) made of aluminum was obtained. The content ratio ofthe particles made of aluminum in this dispersion liquid was 3.7% bymass.

Next, as to the dispersion liquid including the particles made ofaluminum obtained as described above, 20 parts by mass of2-(perfluorohexyl)ethylphosphonic acid was added with respect to 100parts by mass of the particles made of aluminum and the surfacetreatment of the particles made of aluminum was performed while thedispersion liquid was irradiated with ultrasonic waves at solutiontemperature of 55° for 3 hours. After the reaction finished, theparticles made of aluminum were redispersed by centrifuging andprecipitating the particles made of aluminum which were subjected to thesurface treatment using a centrifugal separator (6,000 rpm×30 minutes),discarding a supernatant liquid portion thereof, adding diethyleneglycol diethyl ether, and further irradiating the dispersion liquid withultrasonic waves and the dispersion liquid (the redispersion liquid) inwhich the content ratio of the particles made of aluminum was 3.7% bymass was obtained. This redispersion liquid was condensed using anevaporator and a paste-like dispersion liquid (dispersion medium:diethylene glycol diethyl ether) in which the content ratio of theparticles made of aluminum was 10% by mass was obtained (hereinafter,the dispersion liquid thus obtained also referred to as “afluorine-treated pigment dispersion liquid 1”). The volume averageparticle diameter and the average thickness of the particles made ofaluminum thus obtained were respectively 0.8 μm and 20 nm.

3.1.2. Example 2

One in which the dispersion liquid of particles made of aluminumobtained in Example 1 was further warmed at 120° for 3 hours was used.

3.1.3. Examples 3 and 4 and Comparative Example 1

The pigment dispersion liquids of particles made of aluminum which weresubjected to the surface treatment in the same way as Example 1, exceptsetting the additive amount of 2-(perfluorohexyl)ethylphosphonic acid tothe amounts described in Table 1, were manufactured.

3.1.4. Examples 5 to 7

The pigment dispersion liquids of particles made of aluminum which weresubjected to the surface treatment in the same way as Example 1, exceptchanging the fluorine-based compound used for the surface treatment toones described in Table 1, were manufactured.

TABLE 1 Amount of surface treat- ment agent with respect AverageConstitutional Surface to 100 parts by mass particle Average material ofbase treatment of base particles diameter thickness particles agent(part by mass) Shape [μm] [nm] Example 1 Al FHP 20 Plate 0.8 20 Example2 Al FHP 20 Plate 0.9 20 Example 3 Al FHP 10 Plate 1.0 19 Example 4 AlFHP 4.5 Plate 1.0 20 Example 5 Al FBPA 20 Plate 1.1 21 Example 6 Al FOS20 Plate 1.0 22 Example 7 Al FOC 20 Plate 1.0 20 Comparative Al FHP 3Plate 0.9 18 Example 1

Moreover, the abbreviations of the surface treatment agents shown inTable 1 are respectively as follows.

FHP: 2-(Perfluorohexyl)ethylphosphonic acid

FHPA: 2-(Perfluorohexyl)ethylphosphonic acid amine salt

FOS: Perfluorooctane sulfonate

FOC: Perfluorooctane carboxylate

3.2. XPS Analysis

The particles made of aluminum which were subjected to the surfacetreatment were separated by dripping the pigment dispersion liquidobtained as described above to a membrane filter made ofpolytetrafluoroethylene to be filtered. One in which these particlesmade of aluminum which were subjected to the surface treatment weresufficiently dried was set to a sample for the XPS analysis.

Next, the sample for the XPS analysis was fixed on a sample table of anX-ray photoelectron spectroscopy analysis apparatus shown below and theabundance ratio of each element on the aluminum particle surface wasmeasured under the following conditions. The results thereof are shownin Table 2.

X-ray photoelectron spectroscopy analysis apparatus: Type “ESCALAB 250”manufactured by THERMO ELECTRON Co., Ltd.

X-ray light source: Al—Kα ray

Energy: 1486.6 eV

X-ray irradiation angle: 45°

Detection angle: 90°

Spot diameter: 500μφ

Step size: 0.1 eV

Dwell time (the accumulating time at each measurement point): 100 μs

Pass Energy: 20 eV

As to the particles made of aluminum included in the pigment dispersionliquid obtained in Example 1, when the waveforms were separated usingthe Voigt function in an X-ray photoelectron spectroscopy spectrummeasured using the X-ray photoelectron spectroscopy analysis apparatus,it was recognized that there was the peak from 190 eV to 192 eV. Forthis reason, it became clear that 2-(perfluorohexyl)ethylphosphonic acidwas bonded to the surface of aluminum particles. Moreover, the samepeaks in the particles made of aluminum included in the pigmentdispersion liquids obtained in Examples 2 to 5 and Comparative Example1, were recognized.

In addition, as to the particles made of aluminum included in thepigment dispersion liquid obtained in Example 1, the peaks wererecognized at 291 eV and 293 eV in an X-ray photoelectron spectroscopyspectrum measured using the X-ray photoelectron spectroscopy analysisapparatus. Since the peak at 291 eV is a peak derived from —CF₂— and thepeak at 293 eV is a peak derived from —CF₃, it became clear that2-(perfluorohexyl)ethylphosphonic acid exists on the surface of theparticles made of aluminum. Moreover, the same peaks in the particlesmade of aluminum included in the pigment dispersion liquids obtained inExamples 2 to 5 and Comparative Example 1, were recognized.

3.3. Evaluation Test 3.3.1. Evaluation of Dispersibility

10 ml of the pigment dispersion liquid obtained as described above wasadded to a sample bottle and the sample bottle was sealed and storedunder constant temperature of 60° C. for 5 days. The dispersibility wasevaluated depending on how much the pigment dispersion liquid afterstoring can pass through with respect to a filter of 10 μm (manufacturedby MERCK MILLIPORE, MITEX MEMBRANE FILTERS (model number: LCWPO 4700)).The evaluation criteria of the dispersibility are as follows. Theresults of the evaluation test of the dispersibility are shown in Table2.

“A” . . . The passing amount through the filter is 50 mL or more.“B” . . . The passing amount through the filter is 10 mL or more or lessthan 50 mL.“C” . . . The passing amount through the filter is less than 10 mL.

3.3.2. Evaluation of Glossiness

Any one kind of pigment dispersion liquids obtained as described abovewas dripped and applied onto a printing paper (“PM Photo Paper (Glossy)model number: KA450 PSK”, manufactured by SEIKO EPSON CORPORATION) andthe printing paper was dried at room temperature for 1 day. Theglossiness of the particles made of aluminum was evaluated by observingthe obtained sample by sight and by a scanning electron microscope(S-4700, manufactured by Hitachi High-Technologies Corporation,hereinafter, also referred to as a “SEM”). The evaluation criteria ofthe glossiness of the particles made of aluminum are as follows. Theresults of the evaluation test of the glossiness are shown in Table 2.

“A” . . . Excellent in glossiness (excellent in metallic glossiness andhaving specular gloss)“B” . . . Good in glossiness (excellent in metallic glossiness, however,slightly mat tone)“C” . . . Poor in glossiness (no metallic glossiness and exhibiting ablackish-gray color)

3.3.3. Results of Evaluation

In Table 2, the results of the evaluation tests of the dispersibilityand the glossiness of the pigment dispersion liquids obtained inExamples 1 to 7 and Comparative Example 1 are shown.

TABLE 2 Element concentration (atm %) Concentration P ratio Result ofevaluation Al (S or N) C O F F/O F/Al Dispersibility Glossiness Example1 26.6 1.3 17.7 26.1 28.3 1.08 1.06 A A Example 2 26.7 1.3 16.9 26.029.1 1.12 1.09 A A Example 3 29.5 0.6 23.2 29.2 17.6 0.60 0.60 A BExample 4 33.1 0.4 23.2 33.8 9.4 0.28 0.28 B B Example 5 28.2 1.0 19.724.1 27.0 1.12 0.96 A A Example 6 24.6 1.5 18.7 25.3 29.9 1.18 1.22 A AExample 7 25.4 1.2 16.4 25.5 31.5 1.24 1.24 B A Comparative 27.9 0.236.6 30.4 4.9 0.16 0.18 C C Example 1

According to results of the evaluation in Table 2, as to the pigmentdispersion liquid containing the particles made of aluminum in which theconcentration of a fluorine element by the XPS analysis was from 8 atm %to 35 atm %, it was found that the dispersibility became good and theglossiness was also excellent. On the other hand, as to the pigmentdispersion liquid containing the particles made of aluminum in which theconcentration of a fluorine element by the XPS analysis was less than 8atm %, it was found that the dispersibility became defective and theglossiness of the recorded matter was also poor. From the above, as longas the concentration of a fluorine element on the surface of the basemetal pigment by the XPS analysis was at least 8 atm % or more, it wasfound that the sufficient dispersibility was obtained and the glossinessbecame good.

3.4. Evaluation of Solvent-Based Ink Composition 3.4.1. Preparation ofSolvent-Based Ink Composition

Each solvent-based ink composition was prepared with the compositionsshown in Table 3 and Table 4. Specifically, after the solvents and theadditive agents were mixed and dissolved to produce the ink solvent, thepigment dispersion liquid was added to the ink solvent, furthermore, theink solvent was mixed and stirred using a magnetic stirrer for 30minutes at normal temperature under normal pressure to produce thesolvent-based ink composition. Moreover, as to the inks 8 to 11 in Table4, the fluorine-based compound was added to a fluorine-treated pigmentdispersion liquid 3 afterwards so as to be the additive amount describedin Table 4.

For each component described in Table 3 and Table 4, the followingcomponents were respectively used.

Fluorine-treated pigment dispersion liquid 1: the one prepared inExample 1

Fluorine-treated pigment dispersion liquid 2: the one prepared by amethod of manufacturing described below

Fluorine-treated pigment dispersion liquid 3: the one prepared by amethod of manufacturing described below

Fluorine-untreated pigment dispersion liquid: the one prepared in thesame way as Example 1 except not adding2-(perfluorohexyl)ethylphosphonic acid

γ-Butyrolactone: solvent, manufactured by Kanto Chemical Co., Inc.

Diethylene glycol methyl ethyl ether: solvent, manufactured by NipponNyukazai Co., Ltd.

Tetraethylene glycol monobutyl ether: solvent, manufactured by NipponNyukazai Co., Ltd.

Tetraethylene glycol dimethyl ether: solvent, manufactured by NipponNyukazai Co., Ltd.

Tetraethylene glycol monobutyl ether: solvent, manufactured by NipponNyukazai Co., Ltd.

Diethylene glycol diethyl ether: solvent, manufactured by NipponNyukazai Co., Ltd.

Cellulose acetate butyrate: manufactured by Kanto Chemical Co., Inc.,resin, the butylation ratio from 35% to 39%

MEGAFACE F-553: manufactured by DIC Corporation, product name, afluorine-based surfactant

BYK-UV3500: manufactured by BYK Japan KK, product name, a silicone-basedsurfactant

Fluorine-based compound: 2-(perfluorohexyl)ethylphosphonic acid

Preparation of Fluorine-Treated Pigment Dispersion Liquid 2

Firstly, a film which had the smooth surface and was made ofpolyethylene terephthalate (the arithmetical mean surface roughness Rawas 0.02 μm or less) was prepared. Next, cellulose acetate butyrate (thebutylation ratio from 35% to 39%) was applied onto the entire onesurface of this film. Next, a film (hereinafter, also simply referred toas “an aluminum film”) configured of aluminum was formed on the surfaceside onto which cellulose acetate butyrate was applied using anevaporation method.

Next, the film on which the aluminum film was formed was put intodiethylene glycol methyl ethyl ether to be irradiated with ultrasonicwaves. Thereby, the dispersion liquid of plate-shaped particles made ofaluminum (particles to be the base particles) was obtained. The contentratio of the particles made of aluminum in this dispersion liquid was3.7% by mass.

Next, as to the dispersion liquid including the particles made ofaluminum obtained as described above, 20 parts by mass of2-(perfluorohexyl)ethylphosphonic acid was added with respect to 100parts by mass of the particles made of aluminum and the surfacetreatment of the particles made of aluminum was performed while thedispersion liquid was irradiated with ultrasonic waves at solutiontemperature of 55° for 3 hours. After the reaction finished, theparticles made of aluminum were redispersed by centrifuging andprecipitating the particles made of aluminum which were subjected to thesurface treatment using a centrifugal separator (6,000 rpm×30 minutes),discarding a supernatant liquid portion thereof, adding diethyleneglycol methyl ethyl ether, and further irradiating the dispersion liquidwith ultrasonic waves and the dispersion liquid (the redispersionliquid) in which the content ratio of the particles made of aluminum was3.7% by mass was obtained. This redispersion liquid was condensed usingan evaporator and a paste-like dispersion liquid (dispersion medium:diethylene glycol methyl ethyl ether) in which the content ratio of theparticles made of aluminum was 10% by mass was obtained. The volumeaverage particle diameter and the average thickness of the particlesmade of aluminum thus obtained were respectively 0.8 μm and 20 nm.Moreover, when the supernatant liquid portion after centrifuging andprecipitating was discarded, a small amount of supernatant liquidportion was left.

Preparation of Fluorine-Treated Pigment Dispersion Liquid 3

Firstly, a film which had the smooth surface and was made ofpolyethylene terephthalate (the arithmetical mean surface roughness Rawas 0.02 μm or less) was prepared. Next, cellulose acetate butyrate (thebutylation ratio from 35% to 39%) was applied onto the entire onesurface of this film. Next, a film (hereinafter, also simply referred toas “an aluminum film”) configured of aluminum was formed on the surfaceside onto which cellulose acetate butyrate was applied using anevaporation method.

Next, the film on which the aluminum film was formed was put intodiethylene glycol diethyl ether to be irradiated with ultrasonic waves.Thereby, the dispersion liquid of plate-shaped particles made ofaluminum (particles to be the base particles) was obtained. The contentratio of the particles made of aluminum in this dispersion liquid was3.7% by mass.

Next, as to the dispersion liquid including the particles made ofaluminum obtained as described above, 5 parts by mass of2-(perfluorohexyl)ethylphosphonic acid was added with respect to 100parts by mass of the particles made of aluminum and the surfacetreatment of the particles made of aluminum was performed while thedispersion liquid was irradiated with ultrasonic waves at solutiontemperature of 55° for 3 hours. After the reaction finished, theparticles made of aluminum were redispersed by centrifuging andprecipitating the particles made of aluminum which were subjected to thesurface treatment using a centrifugal separator (6,000 rpm×30 minutes),discarding a supernatant liquid portion, adding diethylene glycoldiethyl ether, and further irradiating the dispersion liquid withultrasonic waves and the dispersion liquid (the redispersion liquid) inwhich the content ratio of the particles made of aluminum was 3.7% bymass was obtained. This redispersion liquid was condensed using anevaporator and a paste-like dispersion liquid (dispersion medium:diethylene glycol diethyl ether) in which the content ratio of theparticles made of aluminum was 10% by mass was obtained. The volumeaverage particle diameter and the average thickness of the particlesmade of aluminum thus obtained were respectively 0.8 μm and 20 nm.

3.4.2. Production of Evaluation Sample

An ink cartridge in which the solvent-based ink composition was filledinto a dedicated cartridge for an ink jet printer PX-G930 (manufacturedby SEIKO EPSON CORPORATION) was produced. Next, the obtained inkcartridge was mounted in a black row of the ink jet printer PX-G930 andthe commercially available ink cartridges were mounted in nozzle rowsother than this. Moreover, since the commercially available inkcartridges mounted other than the black row were used as a dummy andwere not used for the evaluation in Examples, these ink cartridges didnot relate to an effect of the invention.

Next, a recorded matter on which a solid pattern image was printed wasobtained by discharging the above-described solvent-based inkcomposition mounted in the black row onto a photo paper <glossy>(manufactured by SEIKO EPSON CORPORATION) using the printer describedabove. Moreover, as to the printing conditions, the discharging inkweight per dot was set to 20 ng and the resolution was set to vertically720 dpi and horizontally 720 dpi.

3.4.2.1. Evaluation of Glossiness

As to the obtained image, the degree of glossiness was measured at aflap angle of 60° using a gloss meter (manufactured by Konica Minolta,Inc., product name “MULTI Gloss 268”). The evaluation criteria of thedegree of glossiness of the obtained image are as follows. The resultsof the evaluation test of the degree of glossiness are shown in Table 3.

“A”: The degree of glossiness is 500 or more.“B”: The degree of glossiness is 400 or more and less than 500.“C”: The degree of glossiness is 300 or more and less than 400.“D”: The degree of glossiness is less than 300.

3.4.2.2. Evaluation of Weather Resistance

The obtained evaluation sample was thrown into a chamber of a xenonweather meter (manufactured by Suga Test Instruments Co., Ltd.) and acycle test of “the light irradiation for 40 minutes”, “the lightirradiation and the rainfall of water for 20 minutes”, “the lightirradiation for 60 minutes”, and “the rainfall of water for 60 minutes”in this order was performed under a test condition of 60 W/m² (300 nm to400 nm). This cycle test was continuously performed for 2 weeks andafter 2 weeks, the evaluation sample was taken out. Then, the evaluationsample which was taken out was left for 1 hour under a generalenvironment. After the evaluation sample was left, as to solid patternforming parts of each recorded matter which was manufactured asdescribed above, the degree of glossiness was measured at a flap angleof 60° using a gloss meter (manufactured by Konica Minolta, Inc.,product name “MULTI Gloss 268”), the lowering rate of the degree ofglossiness was determined, and the evaluation was performed inaccordance with the following criteria.

“A”: The lowering rate of the degree of glossiness is less than 5%.“B”: The lowering rate of the degree of glossiness is 5% or more andless than 15%.“C”: The lowering rate of the degree of glossiness is 15% or more.

3.4.3. Evaluation of Continuous Printing Stability

The evaluation was performed by a test as shown below using eachsolvent-based ink composition which was prepared as described above.Firstly, a liquid droplet discharging apparatus arranged in a chamber (athermal chamber) and each solvent-based ink composition described abovewere prepared and as to each solvent-based ink composition, the liquiddroplets of 2,000,000 shots (2,000,000 droplets) were continuouslydischarged from each nozzle of liquid droplet discharging head in astate of optimizing a driving waveform of a piezo element, under anenvironment of 25° and 55% RH. Afterwards, the operation of the liquiddroplet discharging apparatus was stopped and the liquid dropletdischarging apparatus was left for 240 hours under an environment of 25°and 55% RH in a state in which each solvent-based ink composition wasfilled in a flow path of the liquid droplet discharging apparatus.

Afterwards, the liquid droplets of 4,000,000 shots (4,000,000 droplets)were continuously discharged from each environment of 25° and 55% RH. Asto the liquid droplets of 4,000,000 shots discharged from a specifiednozzle in the vicinity of the center part of the liquid dropletdischarging head after leaving for 240 hours, the average value of thedeviation amounts of the center position of each liquid droplet whichwas impacted from the center of a target position was determined and theevaluation was performed in accordance with the criteria of thefollowing five grades. When this value is smaller, it can be said thatthe occurrence of the flying curving is effectively suppressed.

“A”: The average value of the deviation amounts is less than 0.07 μm.“B”: The average value of the deviation amounts is 0.07 μm or more andless than 0.14 μm.“C”: The average value of the deviation amounts is 0.14 μm or more andless than 0.17 μm.“D”: The average value of the deviation amounts is 0.17 μm or more andless than 0.21 μm.“E”: The average value of the deviation amounts is 0.21 μm or more.

3.4.4. Evaluation of Sedimentation Properties

After 10 mL of each solvent-based ink composition prepared as describedabove was put into a 14 cc centrifuge tube and treated at 3,000 rpm for10 minutes by a centrifugal separator, 0.1 cc of a supernatant thereof(a region under 10 mm from a gas-liquid interface) was collect tomeasure the absorbance (Abs. 500 nm), the concentration was calculatedfrom the calibration curve prepared in advance, and the evaluation wasperformed in accordance with the following criteria.

“A”: The concentration of the supernatant is 50% or more of the initialconcentration.“B”: The concentration of the supernatant is 35% or more and less than50% of the initial concentration.“C”: The concentration of the supernatant is less than 35% of theinitial concentration.

3.4.5. Redispersibility

After 10 mL of each solvent-based ink composition prepared as describedabove was put into a 14 cc centrifuge tube and treated at 3,000 rpm for10 minutes by a centrifugal separator, the solvent-based ink compositionwas shaken 100 times to be stirred. 0.1 cc of a supernatant thereof (aregion under 10 mm from a gas-liquid interface) was collect to measurethe absorbance (Abs. 500 nm), the concentration was calculated from thecalibration curve prepared in advance, and the evaluation was performedin accordance with the following criteria.

“A”: The concentration of the supernatant is 95% or more of the initialconcentration.“B”: The concentration of the supernatant is 85% or more and less than95% of the initial concentration.“C”: The concentration of the supernatant is less than 85% of theinitial concentration.

3.4.6. Results of Evaluation

In Table 3 and Table 4, the compositions of each solvent-based inkcomposition and the results of the evaluation test are shown.

TABLE 3 Kind of solvent-based ink Ink 1 Ink 2 Ink 3 Ink 4 Ink 5 Ink 6Pigment Fluorine-treated pigment dispersion 1.5 1.5 1.5 1.5 1.5 —dispersion liquid 1 (solid content) liquid Fluorine-untreated pigmentdispersion — — — — — 1.5 liquid (solid content) Organic γ-Butyrolactone15 15 10 10 15 10 solvent Diethylene glycol methyl ethyl ether 75 75 — —75.3 — Tetraethylene glycol monobutyl ether 8 8 — — 8 — Tetraethyleneglycol dimethyl ether — — 15 15 — 15 Tetraethylene glycol monobutylether — — 3 3 — 3 Diethylene glycol diethyl ether — — 70 70 — 70.3 ResinCellulose acetate butyrate 0.2 0.2 0.2 0.2 0.2 0.2 Surfactant MEGAFACEF-553 0.3 — 0.3 — — — BYK-UV3500 — 0.3 — 0.3 — 0.3 Result of GlossinessB B A A C D evaluation Weather resistance B A B A B C Continuousprinting stability B A B A C E

TABLE 4 Kind of solvent-based ink Ink 7 Ink 8 Ink 9 Ink 10 Ink 11Pigment Fluorine-treated pigment dispersion liquid 2 1.5 — — — —dispersion (solid content) liquid Fluorine-treated pigment dispersionliquid 3 — 1.5 1.5 1.5 1.5 (solid content) Organic γ-Butyrolactone 15 1515 15 15 solvent Diethylene glycol methyl ethyl ether 75 75 75 75 8Tetraethylene glycol monobutyl ether 8 8 8 8 75 Resin Cellulose acetatebutyrate 0.2 0.2 0.2 0.2 0.2 Surfactant BYK-UV3500 0.3 0.3 0.3 0.3 0.3Fluorine- Post addition of fluorine-based compound No Yes Yes Yes Yesbased Concentration of fluorine-based compound 0.2 0.05 0.5 1.5 1.5compound Results of Sedimentation properties A B A A A evaluationRedispersibility A A A A B

As shown in Table 3, according to the solvent-based ink compositions(the inks 1 to 5) produced using the pigment dispersion liquid ofExample 1, it was found that the recorded matters excellent in degree ofglossiness and weather resistance was obtained and the continuousprinting stability became good. On the other hand, according to thesolvent-based ink composition (the ink 6) produced using thefluorine-untreated pigment dispersion liquid, the recorded matter inwhich the degree of glossiness and weather resistance were not excellentwas obtained. In addition, in a continuous discharging stability test,the deviation amount became very large, and thus it was difficult tosuppress the occurrence of the flying curving. It is considered thatthis is because the clogging at the head portion occurred due to theparticles made of aluminum being flocculated in the solvent-based inkcomposition and the particle diameter being increased. From the above,in a case of preparing the solvent-based ink composition havingglossiness, the advantages by using the fluorine-treated pigmentdispersion liquid were shown.

As shown in Table 4, as to the ink 7 in which the concentration of thefluorine-based compound was adjusted to 0.2% by mass by the isolatedfluorine-based compound remained in the fluorine-treated pigmentdispersion liquid 2, it was found that the base metal pigment treated bythe fluorine-based compound was difficult to precipitate and theredispersibility of the precipitated base metal pigment became good. Inaddition, even as to the inks 8 to 11 in which the concentration of thefluorine-based compound was adjusted from 0.05% by mass to 1.5% by massby adding the fluorine-based compound to the ink composition afterwards,it was found that the base metal pigment treated by the fluorine-basedcompound was difficult to precipitate and the redispersibility of theprecipitated base metal pigment became good. From the above, it wasindicated that sedimentation properties and the redispersibility of thebase metal pigment treated by the fluorine-based compound became gooddue to existing the fluorine-based compound isolated in the inkcomposition with the predetermined amount.

The invention is not limited to the embodiment described above andvarious modifications are possible. For example, the invention includessubstantially the same configuration as the configuration described inthe embodiment (for example, the configuration having the same function,method, and result or the configuration having the same object andadvantage). In addition, the invention includes a configuration in whichan inessential part of the configuration described in the embodiment isreplaced. In addition, the invention includes a configuration whichexhibits the same working effect or a configuration which can achievesthe same object as those of the configuration described in theembodiment. In addition, the invention includes a configurationimparting a well-known art to the configuration described in theembodiment.

The entire disclosure of Japanese Patent Application Nos. 2013-219879,filed Oct. 23, 2013 and 2014-141195, filed Jul. 9, 2014 are expresslyincorporated by reference herein.

What is claimed is:
 1. A pigment dispersion liquid for a solvent-basedink, comprising: a base metal pigment; and an organic solvent, whereinthe base metal pigment is subjected to a surface treatment by afluorine-based compound, and wherein the concentration of a fluorineelement is from 8 atm % to 35 atm % when an X-ray photoelectronspectroscopy (XPS) analysis of the surface of the base metal pigment isperformed.
 2. The pigment dispersion liquid according to claim 1,wherein when an XPS analysis of the surface of the base metal pigment isperformed, the concentration of phosphorus, sulfur, or nitrogen or thetotal sum of these elements is 1 atm % or more.
 3. The pigmentdispersion liquid according to claim 1, wherein the fluorine-basedcompound includes fluorine and one or more kinds selected fromphosphorus, sulfur, and nitrogen as a constitutional element.
 4. Thepigment dispersion liquid according to claim 1, wherein thefluorine-based compound has a perfluoroalkyl group.
 5. The pigmentdispersion liquid according to claim 4, wherein the number of carbonatoms of the perfluoroalkyl group is from 1 to
 6. 6. The pigmentdispersion liquid according to claim 1, wherein when an XPS analysis ofthe surface of the base metal pigment is performed, the ratio ([F]/[O])of the concentration of a fluorine element ([F]; atm %) to theconcentration of an oxygen element ([O]; atm %) is from 0.2 to 1.2. 7.The pigment dispersion liquid according to claim 1, wherein the basemetal pigment includes at least one kind selected from aluminum, iron,copper, nickel, and chromium or an alloy with other metals.
 8. Thepigment dispersion liquid according to claim 7, wherein in a case wherea base metal included in the base metal pigment is aluminum or analuminum alloy, when an XPS analysis of the surface of the base metalpigment is performed, the ratio ([F]/[Al]) of the concentration of afluorine element ([F]; atm %) to the concentration of an aluminumelement ([Al]; atm %) is from 0.2 to 1.1.
 9. The pigment dispersionliquid according to claim 1, wherein the shape of the base metal pigmentis plate-shaped.
 10. The pigment dispersion liquid according to claim 1,wherein the molecular weight of the fluorine-based compound is 1,000 orless.
 11. A solvent-based ink composition, comprising: the pigmentdispersion liquid according to claim 1; an organic solvent; and a resin.12. A solvent-based ink composition, comprising: the pigment dispersionliquid according to claim 2; an organic solvent; and a resin.
 13. Asolvent-based ink composition, comprising: the pigment dispersion liquidaccording to claim 3; an organic solvent; and a resin.
 14. Asolvent-based ink composition, comprising: the pigment dispersion liquidaccording to claim 4; an organic solvent; and a resin.
 15. Asolvent-based ink composition, comprising: the pigment dispersion liquidaccording to claim 5; an organic solvent; and a resin.
 16. Asolvent-based ink composition, comprising: the pigment dispersion liquidaccording to claim 6; an organic solvent; and a resin.
 17. Asolvent-based ink composition, comprising: the pigment dispersion liquidaccording to claim 7; an organic solvent; and a resin.
 18. Thesolvent-based ink composition according to claim 11, wherein thefluorine-based compound which is adsorbed or bonded to the base metalpigment included in the pigment dispersion liquid and the fluorine-basedcompound isolated in an ink composition are included, and wherein thecontent of the fluorine-based compound isolated in an ink composition isfrom 0.01% by mass to 3% by mass.
 19. The solvent-based ink compositionaccording to claim 11, wherein a first organic solvent in which the SPvalue based on the Hansen method is from 7 cal/cm³ to 9 cal/cm³ isincluded as the organic solvent.
 20. The solvent-based ink compositionaccording to claim 19, wherein the content of the first organic solventin an ink composition is from 20% by mass to 95% by mass.